Project Abstract Completely noninvasive neuromodulation using focused ultrasound (FUS) offers the promise of precisely stimulating specific targets deep in the brain, at power levels commonly used for diagnostic imaging studies. Having a working mouse model to study neuromodulation with ultrasound is a critical need. The mouse model has a much wider array of immunohistochemical staining antibodies and known genetic markers to answer basic science questions than do larger animals. In addition, the mouse is considerably easier to study than larger animals. In this project, we aim to study what exactly we are stimulating with ultrasound in the mouse model, from both the behavioral and histologic responses. This is essential for dose/response studies. We will study whether the peripheral hearing system is stimulated by ultrasound. In parallel, we will study what part of the brain is activated as detected by c-fos staining. This will form the basis for an additional study in cell type activation co- localized with c-fos. Lastly, we will study the safety of ultrasound neuromodulation in the mouse brain using immunohistochemistry methods.